Scientists use models to show the structure and bonding of substances. Every model is useful for some things and misleading for others, so you need to know the limitations of each one.
A dot and cross diagram shows the outer electrons of atoms and how they are shared or transferred. It does not show the shape of a molecule, the sizes of the atoms or the lengths of the bonds. It also suggests that electrons are different from each other and sit in fixed places, which is not true.
A ball and stick model shows the three-dimensional arrangement of atoms and the bonds between them. However, the sticks suggest that bonds are solid rods, and the model does not show the electrons. The gaps between the atoms are far too large, and the atoms are not really round, separate balls.
A two-dimensional diagram is easy to draw, but it cannot show the real three-dimensional shape or the true angles between bonds. A three-dimensional model shows the shape more accurately, but it is harder to draw and can hide atoms behind others.